seminar on Optic Atrophy

OPTIC ATROPHY

INTRODUCTION DEFINITION:Optic atrophy can be defined as

damage to the optic nerve resulting in a degeneration or destruction of the optic nerve.

Final endpoint of any disease process causing

axon degeneration Clinically, manifests as changes in the color &

structure of optic disc Variable degrees of visual dysfunction. Actually a misnomer Actually,atrophy refers to involution of a

structure resulting from prolonged disuse.

OPTIC NERVE

IInd cranial nerve (neurosensory)

Comprises approximately 1.2 million axons

Originate at the ganglion cell layer of the retina.

The axons are myelinated by oligodendrocytes,

The axons do not regenerate.

Behaves more like a white matter tract  

VISUAL PATHWAY Unilateral

atrophy Lesion involving

anterior to optic chiasm

Bilateral atrophy Lesion involving

chiasm &optic tract

The optic nerve is divided into the

following 4 parts:

1. Intraocular part =optic nerve head (1 mm)

2. Intraorbital part (25 mm)

3. Intracanalicular part (5 mm)

4. Intracranial part (10 mm)

BLOOD SUPPLY OF OPTIC NERVE

INTRAORBITAL a) Periaxial :ophthalmic

A,Long posterior ciliary A,Short posterior ciliary A,Lacrimal A,Central a of retina

b) Axial : Intraneural br of Central retinal A,Collateral br,Central A of optic N

INTRACANALICULAR Periaxial system INTRACRANIAL: Periaxial Br of int carotid A;Br from

ant cerebral A;small recurrent br from ophthalmic A;Ant communicating A.

INTRAOCULAR1.Surface N. fibre

layer Capillaries from

retinal arterioles2.Prelamiar region Short posterior

ciliary A, Choroidal A3.Laminar cribrosa Short posterior

ciliary A Circle of Zinn-Haller4.Retrolaminar region Pial blood vessels

FEATURES OF NORMAL OPTIC NERVE

NORMAL NERVE FIBRE LAYER OPTIC NERVE ATROPHY

HISTOPATHOLOGIC CHANGES IN OPTIC ATROPHY

Shrinkage or loss of both myelin and axis cylinders Widening of the pial septa Gliosis Deepening of the physiologic cup with barring of

the lamina cribrosa Widening of the subarachnoid space with

redundant dura Severed nerve leads to bulbous axonal swellings

(Cajal end bulbs)

PATHOLOGIC CLASSIFICATION

 Anterograde degeneration (Wallerian degeneration) Deterioration begins in the retina and proceeds toward

the lateral geniculate body (ie, to the brain). Toxic retinopathy, chronic simple glaucoma

Retrograde degeneration Deterioration starts from the proximal portion of the

axon and proceeds toward the optic disc (ie, to the eye). Intracranial tumor

Trans-synaptic degeneration A neuron on one side of a synapse degenerates as a

consequence of the loss of a neuron on the other side. Occipital damage incurred in utero or during early

infancy.

OPHTHALMOSCOPIC CLASSIFICATION

PRIMARY OPTIC ATROPHY SECONDARY OPTIC ATROPHY

GLAUCOMATOUS/CAVERNOUS OPTIC ATROPHYCONSECUTIVE OPTIC ATROPHY

ETIOLOGIC CLASSIFICATION

1) Hereditary 1) Congenital or infantile optic atrophy 2) Behr hereditary optic atrophy3) Leber optic atrophy

2) Consecutive atrophy3) Circulatory atrophy4) Metabolic atrophy :

Thyroid ophthalmopathy, juvenile diabetes mellitus, nutritional amblyopia, toxic amblyopia, tobacco, methyl alcohol, and drugs (eg, ethambutol, sulphonamides).

5) Demyelinating atrophy : multiple sclerosis and Devic disease.

6) Pressure or traction atrophy : glaucoma and papilledema. 7) Postinflammatory atrophy : optic neuritis, perineuritis secondary

to inflammation of the meninges, sinus and orbital cellulites. 8) Traumatic optic neuropathy: Optic nerve avulsion and transection,

optic nerve sheath hematoma, and optic nerve impingement from a penetrating foreign body or bony fragment

ATROPHY

Monocular band optic atrophy Band or "bow tie" optic atrophy Homonymous hemianopia Invovement of fibre entering optic disc

nasally & temporally(sparing superior & inferior portion)

Unilateral visual defect.

DIFFUSE

SECTORAL

Associated with compressive lesions of the pregeniculate post-chiasmal pathway (or)

Congenital malformations of postgeniculate radiations or cortex.

The optic atrophy is strictly U/L

CAUSES After retrobulbar neuritis Tumour & aneurysms Hereditary optic neuropathies Toxic & nutritional optic

neuropathies

PRIMARY OPTIC ATROPHY

Disc is chalky white

Well defined margins

Lamina cribrosa is well defined

Slight cupping shallow,saucer shaped

Surrounding retina is normal

Kestenbaum sign

ETIOLOGY OF POA

Idiopathic Demyelination Post inflammatory Toxic Inflammation of orbit, sinus and meninges Compressive Nutritional Hereditary

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POST INFLAMMATORY

TABES & GENERAL PARALYSIS Inflammation affects pial sheath

resulting in degenerative change Gradual loss of vision Contraction of fields for colours

TREATMENT:Penicillin eradicate infection &arrest optic atrophy

September 2006

19 / 12

ACUTE RETROBULBAR NEURITISIt frequently affects only temporal ½ of discIt occurs in Disseminated sclerosis Loss of blood Focal sepsis & catarrhal disease of nasal sinus Orbital inflammation

InfectiousDiseases:Meningitis/Encephalomyelitis,

Vaccination Nutritional disorder

CHRONIC RETROBULBAR NEURITIS

CAUSES Tobacco(most common) Methyl alcohol,ethyl alcohol Lead Quinine Carbon di sulphide,iodoform,thallium Arsenical preparations

MENINGITIS INCLUDING ARACHNOIDITIS OPTICO CHIASMATICA

Type of atrophy:descending

Arachnoiditis optico chiasmatica Chronic progressive disease affected by direct pressure from membrane,cords or cysts

SIGN U/L or B/L loss of vision Centre or paracentral scotoma Peripheral fields contraction Primary /secondary optic atrophy

Optic arachnoiditis on basal surface of pons & inter peduncular fossa

TREATMENT

Treatment is mainly surgical Freeing of adhesions Libration of cystic fluid

COMPRESSIVE OPTIC NEUROPATHY

Progressive scotoma

Initially normal disc

Signs of atrophy Decrease in color Decrease in

vessels Decrease in NFL

TRAUMA (COMPRESSIVE)

ETIOLOGY Distension of optic sheaths with blood

under pressure By bony fragments due to fracture of

optic foramen

TUMOUR AND BONE DISEASES Tumour in optic nerve,orbit and base of skull Causes pressure atrophy. Growth position indicated by clinical findings

& visual fields.

CAUSES Pituitary tumour Suprasellar meningioma Osteopetrosis(albers schoenberg’s disease) Idiopathic hypercalcemia

Optocilliary blood vessels

SECONDARY OPTIC ATROPHY Disc is grey or dirty

grey Margins are poorly

defined Lamina cribrosa

obscured Peripapillary

sheathing of Artery Tortorous veins Kestenbaum’s sign

SECONDARY OPTIC ATROPHY Ischaemic optic neuropathy Chronic papilloedema Chronic optic neuritis

CAUSES OF SECONDARY OPTIC ATROPHY Infectious Disorders (Specific

Agent) Syphilis General paresis/CNS syphilis deme

ntia

Meningitis, cryptococcal Tabes dorsalis

Granulomatous, Inflammatory Disorders Orbital inflammatory disease

Neoplastic Disorders Kennedy syndrome Sellar tumor/suprasellar extension Meningioma Suprasella tumor

Allergic, Collagen, Auto-Immune Disorders Takayasu's pulseless aortitis synd. Behcet's syndrome

Metabolic, Storage Disorders Tay-Sachs disease Gangliosidosis

, generalized (GM1) Infantile ceroid lipofuscinosis

/Finnish (Santvuori-Haltia) Juvenile ceroid lipofuscinosis

/Batten-M Sandhoff disease

Deficiency Disorders Anemia of malnutrition Malnutrition/Starvation

Congenital, Developmental Disorders Craniofacial dysostosis/

Crouzon Optic atrophy-ataxia syndrom

e

Familial, Genetic Disorders Acrodermatitis

enteropathica Cockayne syndrome Leukodystrophy, Krabbe Optic atrophy, hereditary,

of Leber

Pelizaeus-Merzbacher disease

Brooks syndrome Usage, Degenerative,

Necrosis, Age Related Disorders Multiple sclerosis Optic atrophy, primary

Arteriosclerotic, Vascular, Venous Disorders Optic neuritis, ischemic

Vegetative, Autonomic, Endocrine Disorders Pseudotumor cerebri

/Benign Intracranial Hypertension

Reference to Organ System Optic atrophy, secondary Optic neuritis, acute Pernicious anemia

Drugs Tryparsamide

Administration/Toxicity Suramin (Germanine/

Antrypol) Administration/Toxicity

Khat herbal/intake Poisoning (Specific Agent)

Methanol ingestion/poisoning Lead encephalopathy

GLAUCOMATOUS OPTIC ATROPHY

Marked excavation of optic disc

Posterior bowing of lamina cribrosa

Columnar atrophy Decrease in number &

size of small blood vessels

Increased IOP recession of lamina cribrosa

Cupping depends on IOP Toughness of lamina cribrosa.

Atrophy of the nerve fibers occurs due to IOP vascular sclerosis

The degeneration is of nerve fibers and ganglion cells & inner plexiform &

inner nuclear layers. Glucomatous excavation is due to

atrophy of the nerve disappearance of glial tissue

The duration of increased IOP is the chief factor in causing cupping.

SCHNABEL’S CAVERNOUS OPTIC ATROPHY

Schnabel ‘s theory :cupping of the disc in glaucoma was not due to IOP

Seen in glaucoma without raised IOP

Progressive diminution of blood supply of the nerve disappearance of nerve fibers.

Histologically Mucoid degeneration of the glia

Disappearance of the optic nerve fibers.

Minute cavities in front & behind lamina

Enlarge to form large cavity

Collapse & form cup

front

behind

CONSECUTIVE OPTIC ATROPHY Associated with lesions of retina &

choroid. In chorioretinitis & primary pigmentary

degeneration of the retina. Inflammatory / degenerative lesions. Ascending type

OPHTHALMOSCOPICALLY Yellowish waxy disc Attenuated retinal vessels Changes in the surrounding retina

Optic atrophy in Retinitis pigmentosa

HEREDITARY

INFANTILE HEREDITARY OPTIC ATROPHY Recessive inheritence Loss of vision Constricted visual field Nystagmus

INFANTILE HEREDITARY ATROPHY

BEHR’S DISEASE

LEBER’S DISEASE

CONGENITAL OPTIC ATROPHY

MOTHER SON

BEHR’S OPTIC ATROPHY

Begins in infancy Autosomal recessive Incomplete bilateral optic atrophy with

temporal pallor of both disc Associated with neurological

abnormalities:cerebellar ataxia,spasticity, Pyramidal tract abnomality

LEBER’S OPTIC ATROPHY Bilateral Recessive X-linkage mitochondrial DNA mutation 11778 In adolescent males Unilateral visual defect. Central field defect:pericentral

(or) paracentral scotoma Blindness unusual Colour blindness except blue

& violet Telangiectic microangiopathy

Telangiectic microangiopathy

Severe optic atrophy

DIFFERENTIAL DIAGNOSIS

Axial myopia Optic nerve hypoplasia Brighter-than-normal luminosity Optic nerve pit Myelinated nerve fibers Scleral crescent Optic disc drusen Tilted disc

Optic nerve pit

Temporal crescent

SYMPTOMS

Blurred vision Abnomal side vision Defective color vision Decreased brightness in one eye

relative to the other

WORK-UP OF OPTIC ATROPHY

Visual acuity Colour vision Contrast sensitivity test Pupillary evaluation

Pupil size RAPD(Relative afferent

pupillary defect)

Edge-light pupil cycle time Photostess recovery test Pulfrich phenomenon Cranial nerve examination Extraocular movements Visual field EEG Visually evoked response Imaging technique

B-scan, CT scan,MRI Gadolinium enhanced MRI

PULFRICH PHENOMENON

MRI in multiple sclerosis

BILATERAL OPTIC ATROPHY WITH CENTROCECAL SCOTOMAS

Hereditary (dominant, Leber’s)

Toxic (medications, methanol, heavy

metals) Nutritional (folate,

B12) Demyelinating (optic

neuritis, multiple sclerosis)

CENTROCECAL SCOTOMAS

OTHER INVESTIGATIONS MRI of the brain and orbits with contrast CT scanning of the brain and orbits with contrast :space-

occupying lesion [SOL], sinusitis, hyperpneumatized sinuses, fibrous dysplasia) 

Blood glucose level Blood pressure, cardiovascular examination Carotid Doppler ultrasound study Vitamin B-12 levels Venereal Disease Research Laboratory (VDRL)/Treponema

pallidum hemagglutination (TPHA) tests Antinuclear antibody levels Sarcoid examination Homocysteine levels Antiphospholipid antibodies Enzyme-linked immunosorbent assay (ELISA) for

toxoplasmosis, rubella, cytomegalovirus, herpes simplex virus (TORCH panel)

TREATMENT

Medical Care No proven treatment exists for optic atrophy. Treatment initiated before the development of optic

atrophy can be helpful The role of intravenous steroids is proven in a case

of optic neuritis arteritic anterior ischemic optic neuropathy.

Idebenone, a quinone analog is on trial Leber hereditary optic neuropathy to ameliorate the net ATP synthesis

Stem cell treatment :future treatment of neuronal disorders.

At present, the best defense is an early diagnosis

PREVENTION

Early detection of inflammations Some doctors recommend vitamin C, vitamin

E, coenzyme Q10, or other antioxidants, Avoid tobacco / alcohol Avoiding toxin exposure Avoid nutritional deficiency Early diagnosis and prompt treatment of

compressive & toxic neuropathies Genetic counselling in hereditary disease

Vitamin, Water Soluble Essential to normal metabolism and

DNA synthesis.

Cyanocobalamin (Nascobal) Deoxyadenosylcobalamin and

hydroxocobalamin are active forms of vitamin B-12.

Vitamin B-12 synthesized by microbes Required for healthy neuronal functions

and normal functions of rapidly growing cells.

DOSING

Adult Vitamin B-12 deficiency: 1000 mcg PO once a day

Pernicious anemia or other causes that decrease oral absorption, administer

parenteral injection of 30 mcg IM/Sc once a day for 5-10 d, then 100-200 mcg IM/SC once a month

Intranasal gel: 500 mcg in one nostril once a wk

Pediatric Oral administration:

<12 years: Not established>12 years: Administer as in adults

Alternatively, 100 mcg IM/SC once a day for 10-15 d (total dose of 1-1.5 mg), then 60-100 mcg IM/SC once or twice weekly for several month

Intranasal gel: Not established

FURTHER OUTPATIENT CARE

Low-vision aids for occupational rehabilitation.

PROGNOSIS Early and intensive treatment of cause

provide patients with near-normal vision

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